ATProto is decentralized in that it allows you to choose a 3rd party like Blacksky to do all kinds of things for you. You can use the social media feed this 3rd party curates, use their moderation services like block lists, and even have your data hosted on a 3rd party’s servers.

All while using the same client app everyone else is using, or even a custom 3rd party client.

The nature of the protocol is that everything is connected, but services of the protocol can be decentralized when a user chooses to use a 3rd party to do certain things for them.